Well, no one told me we were looking at profitability with regards to BTC.
That's a whole different ballgame, and all bets are off if you look at it that way! If the price drops drastically, you could see a net profit in BTC quite easily while maintaining a net loss in USD, but if the price increasing drastically, you'd likely never see a profit on your investment vs just investing in BTC directly, while your USD profit would be through the roof.
Consider the following question:
If you spend 11 BTC to buy a device that will produce 10 BTC in its lifetime, will you make any profit?
Or, you could look at it another way:
Is there any exchange rate by which you will profit more by spending 11 BTC to get 10 BTC than you would by just keeping the 11 BTC?
Consider the following counter-question:
If you spend 11 BTC ($1,200) to buy a device that will produce 1,000 BTC ($100 after a huge market crash), will you make any profit?
That's why I assume no change in exchange rate, and why I look at profit in terms of USD and not BTC.
So you admit that spending 11 BTC for a product that will produce 10 BTC is a bad idea.
Anyway, assuming no change in value, I don't see how a BFL ASIC ordered now would NOT turn a net profit eventually (in both BTC and USD), unless there are additional delays beyond their projection of shipping all current preorders by September.
At 100 million difficulty and a 6.5% growth rate per difficulty adjustment, a Jalapeno will not earn back the BTC you could have had at today's exchange rate.
But, back to the profit. Let's say that you are correct, that difficulty is 60,000,000 by the time you receive your shiny new 50GH/s BFL miner.
That assumes that Avalon, Bitfury, and KNCMiner do not deliver anything further. 60,000,000 difficulty is just BFL's known order book.
You spent 24 BTC on it. The miner, at 60,000,000 difficulty, makes 12.74 BTC/month. Also have to assume that difficulty is continuing to rise, and I'm not going to do the calculus, but just assume that difficulty went up 25% and you manage to pull out 10 BTC of the first month. Next month, same thing - difficulty went up 25% over the course of the month, and you get another 8 BTC. Etc, etc, making 6.5 BTC, 5 BTC, 4.5 BTC in the following months. After just the first 3 months, you've already recovered your original BTC amount.
Yes, if no other company besides BFL delivers ASICs, you will profit from buying a BFL unit today.
Use this mining calculator on expert mode:
http://www.coinish.com/calc/#The only reason difficulty would continue to go up is if people continued to buy miners. The only way people would continue to buy miners is if they deem it to return a reasonable profit. Do you think 4.5 BTC/month (and potentially declining) on a 24 BTC purchase is a reasonable profit? I do, but many people certainly don't - not in the volatile world of Bitcoin, anyway. So people like would start dropping out of purchases of miners when the singles start only making 6 BTC a month, or 4.5 BTC a month, or whatever number you want to use. But that still leaves the people who did buy them a net profit after 6 months or less, and it means difficulty would largely stagnate and stop increasing.
I would even wager on a bet that a BFL SC Single would eventually pay itself off in either USD or BTC, electric costs included, if purchased today.
I would not take that bet. Since people are still pre-ordering and ignoring the math, I believe that they will overshoot profitability by quite a bit. Also, second generation ASICs will have a lower price point, higher performance, and run more efficiently. People can still buy those and add to the hash rate long after first generation equipment is no longer profitable to purchase (but while running might earn more than they cost in electricity for quite some time).
If you are banking on a rise in BTC/USD to enhance your profitability, you should just buy BTC and hold it.